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American Community Survey

American Community Survey. Susan Clapp Demographics & Workforce Group U.Va . Weldon Cooper Center for Public Service. What will I learn today?. ACS Basics ACS and the 2010 Census Accessing Data Using survey estimates What to watch out for Resources. What is the ACS?.

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American Community Survey

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  1. American Community Survey Susan Clapp Demographics & Workforce Group U.Va. Weldon Cooper Center for Public Service

  2. What will I learn today? • ACS Basics • ACS and the 2010 Census • Accessing Data • Using survey estimates • What to watch out for • Resources

  3. What is the ACS? • The American Community Survey (ACS) is an ongoing survey that provides data every year -- giving communities the current information they need to plan and to provide services. • Survey data help determine how more than $400 billion in federal and state funds are distributed each year.

  4. What is the ACS? Population Survey Census

  5. Where did the ACS come from? Continuous ACS replaced long form in 2005 • The ACS has its roots in the Decennial Census long form. Basics – age, gender, race, number of people Details – income, education, language spoken, etc. Short form Census every 10 years Short form Census every 10 years Short form and long form Census every 10 years

  6. How has the ACS helped? • Detailed data are available every year, not every 10 years • ACS interviewers are professional, year-round employees, not temporary employees hired every 10 years • Faster, cheaper, and more accurate Decennial Census

  7. What about the 2010 Census? 2010 Census ACS Purpose To show the number of people To show how people in the U.S. live who live in the U.S. Length 10 questions 69 questions Frequency Once, April 1, 2010 Ongoing learn How it should be used To obtain counts of the To about the population’s population and their basic demographic, social, economic, and characteristics housing characteristics Who is questioned The entire population A sample of the population (over 130 million households) (approximately 3 million households each year) Type of data Counts Estimates with margins of error

  8. What can we learn from the ACS? Social Characteristics Demographic Characteristics Housing Characteristics Economic Characteristics learn Financial Characteristics

  9. Who takes the survey? • Resident population of the United States and Puerto Rico – all people living in housing units and group quarters • A “group quarters” is a residence that is managed by an organization providing housing or services for residents (e.g. college dormitories, prisons, and nursing homes). 9

  10. What do I need to know before I access the data? • Three different kinds of estimates (data series) • 5-year estimates for all geographic areas • 3-year estimates for areas with 20,000 or more • 1-year estimates for areas with 65,000 or more • Sample size (number of people surveyed) is not large enough to obtain annual estimates for small geographic areas

  11. What are single- and multi-year estimates? • Data series are named for length of time required to collect sufficient sample • e.g. 1-year estimates are based on data collected over a 1-year period • 3- and 5- year estimates are known as multi-year estimates because they are based on data collected over multiple years

  12. Which estimates do I use? • Use single-year estimates when… • Currency (timeliness) is critical • Researching large areas experience rapid change • Examining year-to-year changes • Use multi-year estimates when… • Reliability of the data is critical • Analyzing data for small areas • Studying smaller populations in large areas • Examining a set of areas in which some areas have only multi-year estimates

  13. When are data released? • New estimates are released every year for all three series Year of Data Release Data Series 2010 2011 2012 Years of Data Collection 1 - year 2009 2010 2011 3 - year 2007 - 2009 2008 - 2010 2009 - 2011 5 - year 2005 - 2009 2006 - 2010 2007 - 2011

  14. Any questions?

  15. Access to Data • American Factfinder • http://www.census.gov • Albemarle County • Greene County • Albemarle and Greene

  16. Census vs. Survey Population Survey Census

  17. Margins of Error • Surveys have error. The ACS tables give you the margin of error so you can use the estimates appropriately.

  18. What do I do with the Margins of Error? • 1) Take a look at them • 2) Calculate the confidence interval • Confidence interval is a range – the Census Bureau is 90% confident that the true population statistic is between A and B A = Estimate – Margin of Error B = Estimate + Margin of Error

  19. Calculating Confidence Intervals A = 490-139 = 351 B = 490+139 = 629 The Census Bureau is 90% confident that the true number of Greene county residents, ages 60 to 64 years old, who own their home, is between 351 and 629.

  20. Calculating Confidence Intervals A = 50-57 = -7 B = 50+57 = 107 The Census Bureau is 90% confident that the true number of Greene county residents who are Asian, 16+, working, and commuting to work in their own vehicle, is between -7 and 107. Beware!!

  21. What do I do with the Margins of Error? • Take a look at them • Calculate the confidence interval • When margins of error are too big, combine estimates for small groups or small geographies – the Demographics & Workforce Group can help with this! • The most important step is #1. Always look at the margins of error of an estimate before using that estimate. If the margin of error is close to or bigger than the estimate, you should take further steps.

  22. What else should I be aware of? • Making comparisons • Do not compare multi-year estimates to single-year estimates • When comparing two areas, only use data from the same data series • If comparing, for example, Albemarle County and Greene County, use the data series they have in common – ACS 5-year estimates

  23. 2005 2006 2007 2008 2009 2010 What else should I be aware of? • Assessing Change • Do not assess year-to-year changes with multi-year estimates • Consecutive multi-year data contains data from overlapping years • The differences in overlapping estimates are driven by the differences in the non-overlapping years. ACS 2005-2009 5-year Estimates ACS 2006-2010 5-year Estimates

  24. What else should I be aware of? • New American Factfinder • The Census Bureau is replacing their data access system with a new website • Right now, all ACS data are on the old system shown in the demo • Timeline • Late spring – Late summer 2011: ACS data will be phased into the new system • Fall 2011: Old Factfinder will be removed • Links • http://factfinder2.census.gov • Tutorials: http://factfinder.census.gov/home/saff/aff2.html

  25. Resources • www.census.gov/acs/www • http://www.census.gov/acs/www/Downloads/handbooks/ACSGeneralHandbook.pdf • http://www.coopercenter.org/demographics/

  26. Susan Clapp (434)982-5690 susan.clapp@virginia.edu

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